APPARATUS FOR PRODUCING A THERMOPLASTIC ARTICLE HAVING AN UNDERCUT CROSS SECTION

Abstract: The equipment comprises a moulding element (16) having a working surface (18) against which a previously-heated sheet (12) of thermoplastic material is urged. The equipment comprises at least one movable element for defining a cavity (38) with an undercut cross section which, in use, encloses a portion of the sheet (12) to be moulded and compressed-air supply means (36) which bring about the deformation of at least one portion of the sheet (12) by means of a jet of compressed air.

Description: APPARATUS FOR PRODUCING A THERMOPLASTIC ARTICLE HAVING AN UNDERCUT CROSS- SECTION The present invention relates to equipment for producing an article made of thermoplastic material and having an undercut cross-section, particularly for internal linings for motor vehicles, such as an internal door-lining panel or a vehicle door-handle integral with the lining panel or fixable thereto. Although the invention has been developed with particular reference to components for the internal fittings of motor vehicles, it is not intended to be limited to this field and can be used whenever it is desired to produce a component having an undercut cross section and composed of a sheet of thermoplastic material which may be covered and which is shaped by thermal compression-moulding. In the specific field of the moulding of sheets of thermoplastic material, considerable difficulties are encountered in the production of the dies when a component with an undercut cross-section is to be produced. In fact, the conventional technique for the thermal compression- moulding of sheets of thermoplastic material consists of compressing the sheet to be moulded between the shaping surfaces of two moulding elements, which involves the need to form the moulding elements wi h movable portions in order to produce projections which are disposed at angles of less than 90° to the direction of the relative movement of the moulding elements. In order to overcome the aforementioned problems, the subject of the present invention is equipment having the characteristics forming the subject of the claims. The present invention will now be described in detail with reference to the appended drawings, provided purely by way of non-limiting example, in which: ' Figure 1 is a schematic, perspective view of a motor- vehicle door having an article produced by equipment according to the present invention, Figure 2 is a section taken on the line II-II of Figure 1, Figures 3 and 4 are schematic views showing the operation of a first embodiment of equipment according to the invention, and Figures 5 and 6 are schematic views showing the operation of a second embodiment of the equipment according to the invention. With reference to Figure 1 , a motor-vehicle door is indicated 1 and a lining panel 2 with a handle 4, which also forms an armrest 6, is fitted on the inner side thereof. The handle may be constituted by a separate component fixed to the lining panel 2 or may form an integral part thereof. As can be seen in Figure 2, the handle 4 has an undercut cross-section having a generally channel-shaped configuration with an arcuate portion 8 and two ends 10 which face one another. With reference now to Figures 3 and 4, the handle is produced by a thermal compression-moulding process, Starting with a previously-heated sheet 12 of thermoplastic material to the outer surface of which an aesthetic covering 14 is applied. A first moulding element, indicated 16, has a working surface 18 of a shape corresponding to that of the arcuate-prof led portion 8 of the handle 4. Two sliders, indicated 20, are movable between the inoperative positions of • Figure 3 and the operative positions of Figure 4 and have respective working surfaces 22 which, in the operative positions of Figure 4, are connected to the working surface 18 of the first moulding element 16. The equipment also comprises a second moulding element 24 which is movable relative to the first moulding element 16 between the two operative positions shown in Figures 3 and 4. The second moulding element 24 has a shaping surface 26 which is intended to be urged against a portion of the inner surface of the sheet 12. The shaping surface 26 of the moulding element 24 has one or more seats for housing respective fixing members 28 each constituted by a metal plate having fixing appendages 30 to which a screw 32 is fixed. A duct 34 in the second moulding element 24 is connected to a compressed-air source (not shown). The duct 34 communicates with a series of holes 36 in the outer surface of the element 24, near its upper, end. The sheet 12 of thermoplastic material is supported in a semi-plastic state on top of the second moulding element 24, after the fixing members 28 have been positioned in the respective seats . The sheet 14 of covering material is kept extended above the sheet 12. The second moulding element 24 is then brought alongside the first element 16 so as to bring the sheet 12 towards the surface 18 of the first moulding clement 16. The covering sheet 14 thus remains interposed between the working surface 18 and the outer surface of the sheet 12. The two sliders 20 are then brought to their operative con igurations shown in Figure 4. In this con igura ion, the sliders 20 define two cavities 38 with undercut cross- sections, each of which encloses a portion 12a of the sheet 12, a corresponding portion of the covering 14, as well as a hole 36 for the supply of compressed air. As the sliders 20 move from the positions of Figure 3 to those of Figure 4, they bend the ends of the sheet 12 towards one another. The handle 4 is formed by the supply of a powerful jet of compressed air into the region 38, by means of the duct 34 and the holes 36, so as to press the heated thermoplastic sheet 12 against the shaping surfaces 18 and 22 of the first moulding element and of the sliders 20. The second moulding element 24 simultaneously exerts pressure on the inner surface of the sheet 12 so as to insert the anchoring appendages 30 of the fixing member 28 in the body of the sheet 12. The jet of compressed air enables the desired undercut cross-section of the handle 4 to be produced without the need to exert the necessary shaping pressure on the inner surface of the sheet with mechanical members, thus avoiding excessive complexity of the moulding equipment. The finished component is removed simply by returning the sliders 20 to their positions of Figure 3 and by moving the second moulding element 24 away from the first moulding element 16. When the sheet has cooled, the covering 14 is fixed firmly to the outer surface of the sheet and the fixing member or members 28 remain anchored to the inner surface of the sheet 12. The fixing members 28 will serve to fix the handle to the lining panel 2 but the fixing members are not intended to be applied if the handle is formed integrally with the lining panel. The technology described above is also particularly advantageous for forming an upset edge along the perimeter of the lining panel 2 . As shown in Figures 5 and 6, in which elements corresponding to those described above are indicated by the same reference numerals, the slider 20 is movable between the operative position of Figure 5 and the operative position of Figure 6 in a direction perpendicular to that in which the two moulding elements 16 and 24 are closed. In the position of Figure 5, the slider 20 defines a cavity 38 which encloses a perimetral portion 12a of the sheet 12 and the hole 36 for supplying the jet of compressed air which presses the portion of the sheet 12 against the shaping surfaces 22 and 18 of the slider 20 and of the moulding element 16. By providing several sliders along the sides of the equipment it is possible to produce an upset edge along the entire perimeter of the panel 2 with simple and cheap moulding equipment.

Claims: CLAIMS 1. Equipment for producing a component made of thermoplastic mater l and having an undercut cross- section, particularly a handle for motor-vehicle doors, comprising a moulding element (16) having a working surface (18) the shape of which corresponds to a portion of the outer surface of the finished component and against which the previously-heated sheet (12) is urged, characterized in that it comprises at least one movable element (20, 24) for defining a cavity (38) which has an undercut cross-section and - in use - encloses a portion of the sheet (12) to be moulded and means (36) for supplying compressed air, in a manner such that the portion of the sheet (12) which is enclosed in the cavity (38) is deformed by means of a jet of compressed air. 2. Equipment according to Claim 1, characterized in that it comprises at least one slider (20) which is movable between an operative position and an inoperative position and has a working shaping surface (22) against which a portion of the outer surface of the sheet is pressed by means of the jet of compressed air. 3. Equipment according to Claim 2, characterized in that the compressed-air supply means (36) are carried by a second moulding element (24) having a shaping surface (26) which acts against a portion of the internal surface of the sheet (12) in use. 4. Equipment according to Claim 3, characterized in that it comprises two sliders (20) for bending towards one another respective edges of the sheet (12) which extend beyond the working surface (18) of the moulding element (16). 5. Equipment according to Claim 4, characterized in that, in their operative positions, the sliders (20) act against the second moulding element (24) forming the cavity (38). 6. Equipment according to Claim 3, characterized in that the second moulding element (24) has a seat for housing a fixing member (28) which is anchored to the inner surface of the sheet during the shaping thereof.

Inventors: CESANO FRANCO, CESANO, FRANCO
Applicants: CESANO FRANCO, CESANO, FRANCO
Application year: 1994
Main classification: B29C51
IPC codes: B29C49, B29C51